* major overhaul of swap UI, to prepare for rewriting guts

* show "undo" after swiping away items from the Updates tab (thanks @Hocuri!)

* fix ETag handling when connecting to nginx mirrors #1737

* fix issues with "Latest" display caused by mishandling time zones #1757

* ignore all unimportant crashes in background services

* do not use Privileged Extension if it was disabled in Settings
